Three-phase load disconnecting switch



July 18, 1967 J. C. CLASON THREE-PHASE LOAD DISCONNECTING SWITCH Filed Jan. 21, 1965 4 Sheets-Sheet 1 INVENTOR j" 1 ZSO 1 BY Mala), M, M Mafia) ATTORNEY July 18, 1967 J. c. CLASON THREE-PHASE LOAD DISCONNECTING SWITCH 4 Sheets-Sheet 2 Filed Jan. 21, 1965 ATTORNEY July 18, 1967 J, c CLASON 3,331,930

THREE-PHASE LOAD DISCONNECTING SWITCH Filed Jan. 21, 1965 4 SheetsSheet 3 TF '1- I I 24 I, [I r PI 34 34 l I IIIIIIL, V

maria-in...

INVENTOR h Lisom 4 Sheets-Sheet 4 J- C. CLASON THREE-PHASE LOAD DISCONNECTING SWIT CH Jul 18, 1967 Filed Jan. 21, 1965 NVENTOR J; N l-as BY Wm a; am

ATTORNEY United States Patent 8 Claims. (Cl. ZOO-48) The invention relates to a three-phase load disconnecting switch, comprising for each phase two fixed contacts parallel to each other as well as a connector link adapted to be moved in the longitudinal direction normal to these two fixed contacts. Each of these connectors is enclosed by a switch cap or cover.

It is the object of the invention to furnish such a threephase load disconnecting switch having a small base and similar construction of the parts operating the connectors in each of three phases.

A further object of the invention is to provide an improved switch, while at the same time affording a construction which saves space.

To this end the invention furnishes a load disconnecting switch of the type mentioned in the preamble, in which a plane perpendicular to all the fixed contacts is intersected by the longitudinal axes of these fixed contacts in points which form the vertices of an equilateral triangle.

The load disconnecting switch according to the invention is provided with a bell housing cap which in the disconnected position of the switch encloses all the movable parts of the switch, while the fixed parts of the switch are accommodated in a housing shell underneath the bell.

The load disconnecting switch according to the invention is constructed in such a way that its switch position can be directly observed, independently of indicating lamps or other indicating devices, because the switch cap of each phase as well as the bell enclosing all the switch caps in the disconnected position of the switch are made of a transparent material, preferably a synthetic material.

Furthermore, in the switch according to the invention, a cylinder is connected with the switch caps, which can be moved relative to a piston rod formed of two concentric tubes and carrying a piston at its lower end. The inner tube of the piston rod ends in the cylinder chamber underneath the piston, while the space between the inner and the outer tube communicates via holes made in the wall of the outer tube with the cylinder chamber above the piston. All the switch caps can be driven jointly from compressed air being fed to the cylinder chambers located beneath and above the piston respectively via the piston which is constructed in the form of two concentric tubes. Thus, when with the switch switched on, compressed air is fed through the space between the inner and the outer tube to the upper cylinder chamber, the connectors leave the fixed contacts and the cylinder impinges with its upper top plate against a magnet system, which holds the top plate. In consequence of this the load disconnecting switch is locked in the disconnected position. During the disconnecting movement the air in the lower cylinder chamber escapes through the inner tube into the atmosphere.

According to the invention the switch is constructed in such a way that the impact of the cylinder against the magnet system at the end of the disconnecting movement is'considerably weakened. Also, it is constructed so that any damage to the respective parts of the switch is prevented because the piston is provided round the mouth of the inner tube with a projecting flat edge. In the cylinder chamber communicating with the inner tube, opposite the piston, is provided a damping device, which comprises a "ice plate fitting loosely in the cylinder and elastically supported in the direction of movement of said cylinder. This plate is provided with a narrow bore, located within the fiat edge of the piston, and is flat on the side turned towards the piston or has a suitable bearing surface to engage and mate with the piston.

The invention will now be explained more fully by reference to the annexed drawing, which illustrates an embodiment of apparatus constructed in accordance with the invention.

FIG. 1 shows a top view of a number of important parts of the switch, with one switch cap for each phase.

FIG. 2a is a longitudinal section along the line IIa--IIa in FIG. 1 showing an outer bell enclosing the switch.

FIG. 2b shows the same longitudinal section for a different embodiment.

FIG. 2c shows a cross-section along the line IIc-IIc in FIG. 2b.

FIG. 3 shows a top view of a switch cap enclosing the connector of one phase, and

FIG. 4 shows a front view of such a switch cap, viewed from the axis of FIG. 1.

FIG. 5 shows, partly in section, along the line VV in FIG. 3 a side view of such a switch cap.

FIG. 6 shows on a larger scale a portion framed by a dotted line in FIG. 2a, which displays the connection of the switch caps with the means for moving the connectors.

FIGS. 7 and 8 show details of this connection.

FIGS. 9, 10 and 11 show diagrams illustrating the operation of the clamping device.

The scale of FIGS. 1, 2a, 2b, 2c, 3, 4 and 5 is the same, while FIGS. 6-11 are on an enlarged scale.

In FIGS. 1 and 2a a housing base is designated by 10, on which base part is located the housing shell 11 shown in section in FIG. 2a. This shell encloses the fixed contact pairs of all the phases, which, however, are not shown in FIG. 2a. FIG. 2a only shows a section of a collar 12, which encloses the fixed contacts of one phase. Above the fixed parts of the switch thus enclosed by the shell 11, FIG. 2a illustrates the movable parts of the switch shown when withdrawn. These parts are enclosed by a bell 13, which is supported by the shell 11. The movable parts of the switch inside the bell 13 consists of the switch cap 14 for the connector, shown in section, which belongs to the fixed contact pairlocated within the collar 12. In this switch cap 14 a projection 15 is present, which serves to fasten the connector. The outer contour of the switch cap 14 is also shown in FIG. 1 by means of the lines 14a. The two internal projections 15 of this switch cap are designated by means of the dotted circles 15a. Furthermore in FIG. 2a inside the bell 13 another switch cap 16 is partly visible. The outer contour 16a is shown in FIG. 1.

Inside the bell 13 in FIG. 2a is further a tube 17 concentric relative to the axis of the bell. The interior 18 of this tube is accessible via a supply pipe 19 in a top member 20a, said top member being secured to the top of the bell 13 and at the same time supporting the tube 17. This supply pipe 19 is also visible in FIG. 1. The tube 17 is surrounded by a further tube 20 concentric therewith, while the space between these two tubes ends in a supply pipe 21 in the top member 20a, which is also visible in FIG. 1. At the lower end the tube 17, its interior 18 projects through a piston 22, so that compressed air can be fed through the supply pipe 19 and through the interior 18 of the inner tube 17 to the chamber beneath the piston 22. The outer tube 20 extends only to the piston 22; at its lower end, however, it is provided with a ring of holes 23, so that compressed air can be fed through the supply pipe 21 and via the space between the tubes 17 and 20 to the chamber above the piston 22. Adapted to move along the piston 22 is a cylinder 24 closed at the bottom, which cylinder is sealed at the top by a top plate 25a. Movement of the cylinder, which can be effected in the downward direction by the feeding of compressed airthrough the supply pipe 19 and in the upward direction by the feeding of compressed air through the supply pipe 21, causes the switch to be closed and opened respectively, i.e. the switch caps containing the connectors are moved jointly downwards for closing the switch and jointly upwards for opening the switch.

For a fuller elucidation of these. movements it will now be explained by reference to FIGS. 3 to 5 how the switch caps of the three phases are interconnected, and by reference to FIGS. 6 to 8 how these caps are coupled with the cylinder 24, which can be moved upwards and downwards.

FIG. 3, as already stated, shows a top view of a switch cap, e.g. of the switch cap 16 with the contour 16a. FIG. 4 is a front view of the switch cap, showing that on one of the long sides a cylindrical member 26, having according to FIG. 4 a height approximately one half that of the switch cap, is fastened by means of a projection 27. Similarly a cylindrical sleeve 28 is fastened by meansof a projection 29. The sleeve 28, again according to FIG. 4,

has a height approximately one half that of the switch cap. Also the member 26 is hollow, for simplifying its production in conjunction with the switch cap, which consists of a high-grade synthetic insulating material. Now the three switch caps are arranged-in such a way that each cylindrical member 26 of one switch cap is insertedinto the cylindrical sleeve 28 of the adjacent switch cap, so that finally the three switch caps form a firmly interlocked coherent unit.

By reference to FIGS. 6 to 8 it will now be explained in what Way this unit consisting of the three switch caps is coupled with the lower end of the cylinder 24 in FIG. 2a.

In FIG. 6 the part of the cylinder 24 and of the switch cap 14 that is framed by a dotted line in FIG. 2a is i1lustrated on an enlarged scale.

However, in explanation of the said coupling by reference to FIGS. 3 to 5 it is first pointed out that each of the switch caps has on the inside a horizontal rib 30, which is integral with the wall of the switch cap and is approximately perpendicular to this wall, and thus, as in FIGS. 4 and 5, is approximately horizontal, and is reinforced by triangular supports 31 and 32. In all the switch caps these ribs 30 are directed inwards, i.e. turned towards the cylinder 24.

According to FIG. 6 the cylinder 24 at its lower end on the outside carries radial projections 34 at three points 120 apart.

At the lower end the cylinder has a flange 33 with recesses facing the fixed projections 34.

A clamping ring 36, of which a section is shown in FIG. 7 and a top view in FIG. 8, is forced by means of a lock ring 38 against the bottom of the cylinder 24, so that three hooked projections of the clamping ring 36 rest against the underside of the ribs 30 and exactly face the fixed projections 34.-The dimensions of the said recesses in the flange 33 are such that the hooked projections 37 can be freely stuck through them and prevent rotation of the clamping ring.

As shown in FIGS. 3 to 5, the three switch caps are rigidly coupled with each other, and also as shown in FIGS. 6 to 8 the unit consisting of these switch caps is also rigidly coupled by means of their ribs 30 with the cylinder 24, so that upon an upward and downward movement of the cylinder 24 in FIG. 2a all the separate connectors are withdrawnfrom the corresponding fixed contacts and the connectors are pushed on the fixed contacts respectively. It is thus possible to close and open the three-phase switch respectively by feeding compressed air to the supply pipes 19 and 21.

In the opened and in the closed position the movable part of the switch, consisting of the cylinder and the switch caps with connectors, is also held magnetically, as will be explained more fully by reference to FIG. 2a. Above the top plate 25a of the cylinder 24, a magnet system 39 isfitted so that the top plate 25a consisting of ferromagnetic material may be held magnetically in place. The magnetic attraction, which holds the movable .part of the switch in the opened position, must be overcomewhen the switch is to be closed, andin the closed position a. ferromagnetic annular disc 41 fixed by the clamping ring 38 to the underside of the cylinder 24 is held by a similar magnet system 42, so that also in the closed position an additional force supplied by the magnet system acts on the switch contacts. This magnetic force must be overcome when the switch is to be opened.

Instead of these magnetic holding devices, purely mechanically operating devices can also be used, as is illus: trated in FIGS. 2b and 2c.

For holding the cylinder 24 in the opened position,

in FIG. 2b a sleeve 51 of a top member 20b is presentv above the top plate 25b of this cylinder. Near its free end the sleeve 51 has two facing tangential slots, each of which intersects the inner wall of the sleeve in one place.

In each of these slots is placed a small round rod 52 of metal. The rods 52 are interconnected by draw springs 53 and form a clamping device for an annular projection 54 of the top plate 25b because the rods 52 are able to snap into an annular groove 55 of the projection 54. With a view to facilitating the insertion of the projection 54 into the sleeve 51, the projection 54 is constructed to be conical from the free end to the top of the annular groove 55. With a view to holding the cylinder 24 in the closed position, a buffer 56 has been fitted on a sleeve 57 similar to the sleeve 51 at the housing base 10. In thesame way as already described, two round rods 52 with corresponding draw springs here again form a clamping device for a lower projection 58 of the cylinder 24. The projections 54 and 58 are effectively made of synthetic material. The sleeves 51 and 57 on the other hand consist of metal. The numeral 56 designates a spring disc, which has the task of receiving the impact as the switch is closed and which in a similar form can also be used in the embodiment according to FIG. 2a.

If desired, a combination of the upper holding device according to FIG. 2a and the lower one according to FIG. 2b, or vice versa, can also be used.

Next, by reference to FIG. 2 a device will be described which effects a weight compensation for the part of the switch that can be moved downwards and upwards. In order to ensure such a weight compensation, three doublearmed levers are provided, of which one is designated in FIG. 2a by 44. These doubleaarmed levers include pivots 45, which can be mounted at the upper, end of the cylindrical member 28. For this purpose in the cylindrical members 26 are fastened bearing pins 46, which support the pivots 45. The upper end of each lever 44 according to FIG. 1 is connected with the adjacent lever by means of a spring 47. The lower end of the double-armed lever 44 is provided either with a roll 48 or with a guide shoe, so that upon the downward rnovementof the movable part of the switch the roll rolls on an inclinedrail 49 and the guide shoeslides on a guide facerespectively, while the spring 47 is tensioned. Since the downward movement of the movable part of the switch is slowed down by the extension of the springs 47 and the upward movement of the movable part of the switch is accelerated by the contraction of the springs 47, the double-armed levers 44 with their springs 47 -and the guide faces and rails 49 respectively actually form a weight compensation for the movable part of the switch.

In fact, if the upper holding device should fail, owing to the weight of the movable part of the switch the switch might be moved, which is now made impossible by the above-mentioned weight compensation.

For holding the bell 13 and the parts accommodated therein in such a way that they can be disengaged, this bell is connected with the housing base by means of a bayonet joint. The bell can only be removed in the opened position of the switch.

It is effective for the bell 13 as well as the switch caps of all three phases, i.e. beside the switch cap 14 also the two other switch caps belonging to the two other phases and not shown in the drawing, to be made of a transparent material, preferably of a transparent synthetic material. Thus, the isolating condition of the switch caps and the operating condition of the switch can be directly observed independently of indicating lamps or other indicating devices, with which failures in operation are not entirely unexpected and whose indication can moreover be misinterpreted. In fact, when the load disconnecting switch is disconnected, all the switch caps, i.e. in particular the switch cap 14 shown in the drawing, are located inside the respective bell 13 and the space between the lower edge of these switch caps. The upper edges of the corresponding collars of the fixed contacts, e.g. of the collar 12, as well as the condition of the switch caps, are plainly visible.

In this way no mistakes as to the operating condition of the switch can arise, for in the closed position of the switch the switch caps have been pushed completely on the corresponding collars and the bell 13 appears to be practically empty, because in fact also the cylinder 24 and all the other parts inside the bell 13 indicated further in FIGS. 2a, 2b have been pushed into the housing shell 11 and only the piston rod 17, 20 is present inside the bell 13.

When on the other hand the load disconnecting switch is opened, not only all three transparent switch caps, but also the other movable parts of the switch are inside the bell and its interior is filled with all these parts to such an extent that any mistaking of operating condition for that of the closed switch is inconceivable.

When the load disconnecting switch according to the invention is to be switched on, compressed air is fed through the inner tube 17 to the lower cylinder chamber, and the cylinder 24 with the movable switch parts attached thereto is moved downward relative to the stationary piston 22. When the switch is to be disconnected, compressed air is fed to the upper cylinder chamber through the space between the inner tube 17 and the outer tube 20 and through the holes 23, and the cylinder 24 is moved upward. At the end of the disconnecting movement of the cylinder 24 a top plate 25a impinges against the magnet system 39 and the switch is thus locked in the disconnected position. Through this impact certain parts of the switch are apt to be damaged.

To avoid this, the last part of the disconnecting movement is damped, by the air flowing off to the atmosphere from the lower cylinder chamber through the inner tube 17 (see FIG. 2a). For this purpose the piston 22 is provided at its lower end with a projecting fiat edge 62, which surrounds the mouth of the inner tube 17. Fitted in the lower cylinder chamber is a plate 59 fitting loosely in the cylinder 24, which plate is held at some distance from the lower cylinder end by a spring 60. The plate 59 is provided with a narrow bore 61, which lies within the edge 62. The top of the plate 59 is also flat and thus can rest air-tight against the edge 62.

The operation of the damping device follows from FIGS. 9, 10, and 11, in which for similar parts the same reference numerals as in FIG. 2a are used.

In FIG. 9 the cylinder 24 is moved upward to disconnect the switch, and the air in the lower cylinder chamber escapes through the inner tube 17. Owing to the ample clearance between the plate 59 and the wall of the cylinder 24 this air can leave the chamber underneath the plate 59 practically unhindered. In FIG. 10 the plate 59, which has moved upward with the cylinder 24, has just reached the piston 22. The plate 59 now rests with its flat top air-tight against the equally flat edge 62 of the piston 22, so that the remaining air underneath the plate 59 can only escape through the bore 61 in said plate 59. Since the diameter of this bore 61 is only a fraction of the diameter of the inner tube 17, the flowing-out of the air is considerably impeded and the pressure underneath the piston 22 rises. Owing to this rise of pressure and likewise owing to the compression of the spring 60 the cylinder 24 is thus slowed down at the end of its disconnecting movement, so that the impact of the top plate 25a against the magnetic system 39 is amply weakened. FIG. 11 finally illustrates the completely disconnected position of the on-load disconnecting switch.

What I claim is:

1. A load disconnecting switch comprising for at least one phase two fixed contacts, a connector link, and a device for linearly moving said connector link to bridge the two fixed contacts in one position of movement and withdrawn out of bridging engagement with said contacts in another position of movement, including switch caps wherein the devices for moving the connectors are located between said switch caps containing the connectors, which switch caps are Withdrawn with said link from the fixed contacts.

2. An apparatus according to claim 1, including a fixed piston rod provided at its lower end with a piston, and a cylinder chamber which can be moved relative to said piston rod.

3. An apparatus according to claim 2, characterized in that the piston rod has the form of a tube and that its interior ends in the cylinder chamber beneath the piston, the piston rod being surrounded by a second tube with at least one aperture permitting the space between the two tubes to communicate with the cylinder chamber above the piston.

4. An apparatus according to claim 1, characterized in that double-armed levers are provided with intermediate pivots fitted rigidly relative to the switch caps and the upper arms of which are interconnected to the device for moving the connector links by means of springs, and inclined guide faces in the housing shell enclosing the fixed contacts causing the levers to pivot against said springs when the device moves downwardly with aid of the force of gravity.

5. An apparatus according to claim 1, characterized in that each switch cap has a bell enclosing all the switch caps, which bell and cap arrangement in the disconnected position of the switch consists of a transparent material, preferably of a transparent synthetic material.

6. An apparatus according claim 3, characterized in that the piston is provided round the mouth of the inner tube with a flat projecting edge, a damping device which comprises a plate fitting loosely in the cylinder chamber and elastically supported in the direction of movement of the cylinder, which plate is provided with a narrow bore, located to contact a region within the flat edge of the piston communicating with said inner tube, and which plate is flat on the side turned towards the piston to comprise a suitable bearing surface for sealing against said flat projecting edge.

7. A three phase load disconnecting switch, comprising for each phase two fixed contacts and a connector link for bridging said two fixed contacts, a driving device supporting the three connector links and being disposed along the longitudinal axis of the switch to move the connector links to and from the respective fixed contacts, said fixed contacts and said connector links being arranged symmetrically about said driving device, characterized in that each of the connector links is enclosed in a switch cap of insulating material, and that the driving device for moving the connector links includes a stationary piston rod provided at its lower end with a piston and a cylinder which can be moved relative to said piston rod and which is rigidly connected to the switch caps, said piston rod being constituted by two coaxial tubes, the inner tube merging into the cylinder chamber beneath the piston, the outer tube being provided with at least one aperture per- 7 mitting the space between the two tubes to communicate with the cylinder chamber above the piston, said cylinderbeing movable with respect to the piston in either direction by means of a pressure medium supplied to the inner tube or to the space between inner tube and outer tube.

8. An apparatus according to claim 7, characterized in that three double armed levers with intermediate pivots connected rigidly to the switch caps are provided, the upper arms of said levers being interconnected by means of springs, while the lower arms are adapted to slide on inclined guide faces or to roll on inclined rails so as to stress the springs when the connector links are moved 8 towardstt 'he fixed contacts, providing a weight compensation for the movable parts of the ,switch.

References Cited UNITED STATES PATENTS 2,190,402 2/1940 Curzon 200-16 X 2,683,198 7/1954 Bengtsson 200-16 X 7 2,785,241 3/1957 Watson 200-16 10 ROBERT K. SCHAEFER,'Primary Examiner.

H. HOHAUSER, Assistant Examiner. 

1. A LOAD DISCONNECTING SWITCH COMPRISING FOR AT LEAST ONE PHASE TWO FIXED CONTACTS, A CONNECTOR LINK, AND A DEVICE FOR LINEARLY MOVING SAID CONNECTOR LINK TO BRIDGE THE TWO FIXED CONTACTS IN ONE POSITION OF MOVEMENT AND WITHDRAWN OUT OF BRIDGING ENGAGEMENT WITH SAID CONTACTS IN ANOTHER POSITION OF MOVEMENT, INCLUDING SWITCH CAPS WHEREIN THE DEVICES FOR MOVING THE CONNECTORS ARE LOCATED BETWEEN SAID SWITCH CAPS CONTAINING THE CONNECTORS, WHICH SWITCH CAPS ARE WITHDRAWN WITH SAID LINK FROM THE FIXED CONTACTS. 